A problem that can potentially plague shared media type networks is the possibility that an intruder may attempt to enter the network by using the addresses of active nodes in the network. The imposter node attempts to communicate with one or more target nodes by pretending to be an active node on the network. If the imposter node remains undetected, network security is compromised with the result being possible malicious attacks on the network such as causing one or more nodes to execute commands generated by the imposter. The integrity of the network may be compromised with the possible loss of data, breach of security, disruption of network traffic and the loss of communications between nodes. Further, an intruder node may attempt to interfere with network communications by jamming other nodes and preventing them from communicating over the network. The intruder may have knowledge of the protocol in use and is thus able to effectively jam communications by transmitting noise or other signals at the appropriate point(s) in time.
A diagram illustrating an example network comprising an imposter, victim and receiver/destination node is shown in FIG. 1. In this example network, generally referenced 10, a plurality of nodes is adapted to communicate over the shared media 12. An imposter node 14 fakes the address of a victim node 16 and sends packets to the receiver/destination node 18 with the source address of the victim node. Without any intruder detection capability, the receiver receives, decodes and processes the packet believing the packet was sent from the victim when in reality it contains commands from the imposter.
Even if the victim node has the capability of detecting the intruder, it might not be able to communicate the presence of the intruder to the receiver node if the imposter node has the capability of jamming the receiver node. The imposter node may have knowledge of the MAC protocol and can effectively jam the receiver preventing the victim node from notifying the receiver node.
There is thus a need for a shared media based communications network to be able to detect attempts by an intruder to enter into the network. Further, the network should be able to detect when an imposter is attempting to jam one or more other nodes.